#!/bin/bash

# http://www.alfredklomp.com/programming/shrinkpdf
# Licensed under the 3-clause BSD license:
#
# Copyright (c) 2014, Alfred Klomp
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.


shrink () {
  gs					\
	-dNOPAUSE -dBATCH -dSAFER		\
	-sDEVICE=pdfwrite			\
	-dPDFSETTINGS=$3			\
	-dEmbedAllFonts=true			\
	-dSubsetFonts=true			\
	-dAutoRotatePages=/None		\
	-dColorImageDownsampleType=/Bicubic	\
	-dColorImageResolution=$4		\
	-dGrayImageDownsampleType=/Bicubic	\
	-dGrayImageResolution=$4		\
	-dMonoImageDownsampleType=/Bicubic	\
	-dMonoImageResolution=$4		\
	-sOutputFile="$2" "${@:5}"	\
	"$1"
}

usage () {
	echo "Reduces PDF filesize by lossy recompressing with Ghostscript."
	echo "  Usage: $1 infile [outfile] [preset(/printer)] [image-dpi(300)]"
	echo "  Presets available (ascending quality): /screen /ebook /printer /prepress"
}

infile="$1"

# Need an input file:
if [ -z "$infile" ]; then
	usage "$0"
	exit 1
fi

outfile="${2:-$1}"
if [ "$infile" = "$outfile" ]; then
    infile="${1%.*}-original.pdf"
    mv "$1" "$infile"
fi
quality="${3:-"/printer"}"
res="${4:-300}"

shrink "$infile" "$outfile" "$quality" "$res" "${@:5}" || exit $?

[ ! -f "$infile" -o ! -f "$outfile" ] && exit 0
ISIZE="$(echo $(wc -c "$infile") | cut -f1 -d\ )"
OSIZE="$(echo $(wc -c "$outfile") | cut -f1 -d\ )"
if [ "$ISIZE" -lt "$OSIZE" -a $# -lt 5 ]; then
    echo "Shrinking was not successfull, doing straight copy!"
    cp "$infile" "$outfile"
    [ "$1" = "$outfile" ] && rm $infile
fi
